CA1243661A - Chain hoist with automatic brake and double chain hooks - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A pair of axially aligned input and output shafts are journalled from a frame supporting a brake drum about the output shaft and the output shaft mounts two pairs of diametrically opposite brake shoes therefrom spring biased into friction braking relation with the inner surfaces of the drum. One pair of brake shoes are of the self-energizing type to break the output shaft against rotation in one direction relative to the drum and the other pair of shoes are of the self-energizing type for frictionally braking the shaft against rotation in the other direction relative to the drum. Con-necting structure is provided establishing a limited loss motion connection between the shafts and includes control structure to release one pair of the brake shoes responsive to torque input to the input shaft above a predeter-mined minimum in the first direction and to release the other pair of brake shoes responsive to an equal amount of torque input to the input shaft in the opposite direction. Further, brake release structure is provided for shifting all of the brake shoes toward release positions thereof only when torque loading on the output shaft in either direction is below a predeter-mined low value.

Description

3~6~
The instant invention relates to an improved portable chain hoist including a load lifting chain passed over a supporting sprocket therefor and including a pair of depending load supportable ends. Journalled torque input and torque output ~hafts are provided with the output shaft drivingly coupled to the sprocket and brake structure is operatively associate~ with the outpu~
shaft for braking the latter in both direction6 of rotation. Torque tran~fer structure drivingly connects the input shaft to the output shaft through a lost motion connection and is operative to release the brake structure upon the input of rotary torque to the input shaft above a predetermined minimum.
Various different forms of hoist structures and winch structure~ pro-vided with automatic brakes as well as other brake structures including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 1,142,908, 1,877,~08, 1,942,534, 1,990,163, 1,993,744, 2,569,108, 3,054,597, 3,252,189, 3,333,821 and 3,554,337. However, these previously known structures do not include the overall combination of operational features of the instant invention which result in a portable chsin hoist or the like including automatic brake structure as well as a manually operable brake release operable only when the hoist is free of a supported load of any magnitude.
The chain hoist of the instant invention comprises a portable hoist and may be used efficiently and with complete safety to raise and lower a load.
In addition, the hoist is constructed in a manner whereby a load may be trans-ferred from one location to another by utilizing lifting or tension forces alternately on the opposite free ends of the lifting chain of the hoist.
The hoist includes automatic brake structure which is of the self-energizing type and includes brake shoes which are both spring biased and wedge actuated for unfailing reliability.
The main object of this invention i8 to provide a portable chain hoist incorporating an automatic brake structure.
Another object of thi3 invention is to provide a portable chain ~2~36~

hoist which may be used to transfer a load from one location to another.
Still another important object of this invention is to provide a chain hoist inc'luding a brake release mechanism to allow "free wheeling" of the lift chaln portion of the hoist only when the lift chain is free of a load supported therefrom.
A further object of this invention is to provide a chain hoist which is highly portable.
Yet another important object of this invention is to provide a portable chain hoist of the manually actuatable type, but which could be readily modified to be power actuated.
A final object of this invention to be specifically enumerated herein is to provide a chain hoist in accordance with the preceding objects and which will conform to conventional forms of manufact.ure, be of simple constructions and easy to use so as to provide a device that will be economically feasible, long -lasting and relatively trouble free in operation.
Therefore, a chain hoist is provided which includes a support frame, rotatable input and output shafts journalled from the frame, stationary means mounted from the frame and first and second self-energizing wedge-type brake shoe means shiftably mounted from the output shaft for movement between applied and released positions. The first and second brake shoe means are respectively provided with first and second spring means which yieldingly bias the .~

- 2 mls/SS

- ~2~

first and second brake shoe means to the applied positions thereof for friction braking of the output shaft relative to the drum to prevent rotation of the output shaft relative to the drum in first and second opposite directions respectively. The hoist is provided with a torque inpllt member mounted on the input shaft for rotation therewith an~
connecting means drivingly coupling the input and output shafts for rotation of each by the other in opposite directions of rotation. The connecting means includes means establishing a limited loss motion connection between the shafts and control means operative to release the first and second brake shoe means responsive to torque input to the input shaft through the connecting means and to the output shaft above a predetermined minimum in the second and first - directions of rotation respectively. The control means also includes abutment means engagable with the second and first brake shoe means for shifting the second and first brake shoe means to the released positions thereof against the biasing action of the second and first spring means responsive to the torque input to the connecting means from the input shaft in the second and first directions respectively, during the take up of the lost motion in the connection as a result of rotation of the input shaft in the second and firs~ directions, respectively, relative to the output shaft.
Figure 1 is a perspective view of the chain hoist of the instant invention;

~ _ 2a mls/SS

~3~ilE;i~

Figure 2 is an enlarged fragmentary end elevational view of the chain hoist internal reduction gear assembly;
Figure 3 is a side elevational view of the internal working components of the chain hois~;
Figure 4 is an enlarged transverse vertical sectional view of the brake assembly components of the chain hoist;
Figure 5 is a fragmentary exploded perspective view of the internal working components of the chain hoist;
Figure 6 is an enlarged vertical sectional view taken substantially upon the plane indicated by the section line 6--6 of Figure 3;
Figure 7 is an enlarged end elevational view of - the brake release actuating mechanism; and Figures 8 and 9 are perspective views illustrating two diff.erent - 2b -mls/SS

~; ~r ~

3~

manners in which the chain hoi~t may be used.
Referring now more specifically to the drawings, the numerfll 10 generally designates the chain hoist of the instant invention. The chain hoist 10 includes a support frame or outer housing 12 from which anchor means in the form of a pivotally mounted hook 14 i~ supported. The frame or housing 12 rotatably ~journals axially aligned first and (~econd input and output shafts 16 and 18 therefrom through the utilization of any suitable forms of bearings (not shown) and the end of the input shaft 16 adjacent the output shaft 18 supports a torque transfer unit 20 therefrom including a central recess 22 in which the adjacent end of the output shaft 18 is rotatably received. Further, the end of the input shaft 16 remote from the output shaft 18 removably supports a ratchet gear 23 thereErom with which the base end 24 of an operating handle or lever 26 is operatively engaged in any well known manner. The base end 24 is oscillatably supported from the frame or housing 18 and includes a ratchet reversing actuator (not shown) under the control of a control rod 28 extending outward along the lever or handle 26 for manual shifting between limit positions angularly displaced approximately 180 apart.
The frame or housing 12 also ~ournals the combined chain sprocket and load shaft 30 therefrom through the utilization of any suitable form of bearings (not shown) and the shaft 30 includes a chain sprocket portion 32 about which a link chain section 34 is trained. The link chain section 34 includes opposite end portions 36 and 38 equipped with load supporting elements such as hooks 40 and 42, respectively. The shaft 18 includes a gear wheel 44 thereon meshed with a larger diame~er gear wheel 46 carried by the shaft 30.
A brake drum 48 is mounted within the housing 12 by an integral mounting flange 50 and the shaft 18 supports a load locking plate or block therefrom against rotation relative thereto. The load locking block 52 is disposed within the drum 48 and supports two pairs of brake shoes 54 and 56 ~243~
therefrom with the brake shoes of each pair being disposed on diametrically op~posite sides of the shaft 18. Compression sprin~s 60 bias the shoes 54 in one direction and compression springs 62 bias the brake shoes 56 in the opposite direction. In addition, each of the brake shoes ~;4 and 56 includes an arcuate wedge surface S4 engaged with a corresponding roller 66 rotutably mounted from fln ad;acent porc ion oE the block 52 and an expansion ~pring 68 is connected between each shoe 54 and 56 and the adjacent portion of the block 52.
rhe block 52 defines a pair of diametrically opposite axially 10 extending notches 70 and the torque transfer unit 20 includes a pair of axially extending arms 72 loosely received in the notches 70 and provided with opposite side grooves 74 in which end caps 76 carried by the shoes 54 and 56 are received. In addition, a brake release actuator plate 78 is slidable on the input sha~t lfi and a compression spring 80 i9 disposed about the shaft 16 between the torque transfer unit 20 and the plate 78.
The plate 78 includes four brake release pins 82 which extend in a direction paralleling the shaft 16 and the free ends of the pins 82 are bevelled as at 84 and project slightly into the grooves 74 whereby the plate 78 i9 keyed or splined to the torque transfer unit 20 and thus relative to the shaft 16 20 against rotation relative thereto.
A brake release lever 86 is pivotally mounted within the frame 12 by pivot pin portions 88 and loosely embraces the shaft 16. The furcations 90 of the lever 86 include abutment8 92 for abutting engagement with the side of the plate 78 opposite from the side thereof from which the pins 82 project and the lever 86 includes a small diameter control arm 94 which projects outwardly through a slot 96 formed in the housing 12 and in whose opposite ends the free end of the control arrn 94 may be seated. When the control arm 94 is seated ir~ the left end of the slot 96 as illustrated in Figure 1 or the drawings, the brake release lever 86 is in the inactive position, but 30 when the arm 94 is seated in the right end of the slot 96, the brake release ~4~
lever i8 in the active position with the abutments 92 thereof engàged with the plate 78 and displacing the latter to the left a~ viewed in Figure 3 o the drawings whereupon the bevelled ends of the pins 72 will engage the end c~ps 76 to shift all of the shoes 54 and 56 in directions against the biAsing action of the springs 60 and 62.
In operation, the link chain section 34 is pa~sed ove~ the sp~ocket wheel 32 and either end of the section 34 may be uaed to support a load. Then, upon oscillation of the handle 26 in the appropriate manner that load may be raised or lowered, depending upon the setting of the ratchet mechanism (not shown). Whenever the low minimum input torque is applied to the lever in opposition to the load supported by the loading engaging end of the section 34, the springs 60 and 62 as well as the cam surfaces 64 and rollers 66 serve to frictionally engage the brake shoes 54 and 56 with the interior surfaces of the drum 48 and to thus prevent rotation of the output shaft 18 and thus the shaft 30. It will be noted, from Figurs 4, that the ~hoes 54 are of the self-energi~ing type when the shaft 18 tends to ro~ate in a clock-wise direction and that the shoes 56 are of the self-energizing type when the shaft 18 tends to rotate in a counterclockwise direction.
However, when the lever or handle 26 is used to impart above minimum rotational torque to the shaft 18 in a clockwise direction as viewed in Figure

4, the arms 72 cock slightly in the notches 70 and, before engaging the oppos-ing wall of the notches 70, engage the end caps 76 to displace the shoes 54 in a clockwise direction relative to the block 52 and thus release the brake shoes 54 which were only lightly applied. The springs 68 enga~e with the shoes 54 tend to inwardly retract the latter away from the drum 48 and con-tinued rotation of the unit 20 in a clockwise direction then allows the arms 72 to engage the opposing extremities of the notches 70 to thus displace rollers 66 engaged with the shoes 56 downwardly along the ramp surfaces 64 ,~j, of the shoes 56 and to release shoe356.0f course, by this time the rotary torque applied to the lever or handle 26 is equivalent to that necessary to ,,, suspend the load carried by the corresponding end of the chain section 43 and the loaA may be raised as desired.
In addition, the lever or handle 26 may be operated to turn the shnEt 18 in a counterclockwise direction. In such instance, rotation oE tlle unit 20 in a counterclockwise direction will callse the arins 72 ~o el~a~e the end c~p~
76 carried by the shoes 56 and thereby displace the shoes 56 from their fully applied braking positions and the load being supported may be lowered. Also, it will be readily understood that the above described raising and lowering af a load supported from the ch.3in section 34 may be accomplished independent of which end portion of the chain section 34 the load is supported from.
With attention now invited more specifically to Figure 8 of the drawings, it may be seen that the hoist 10 may be inverted relative to the position thereof illustrated in Figure 1 with the hook 14 engaged with a load L and that the hoist 10 may first be used to raise the load 12 toward an anchor A by one end portion of the chain section 34 and thereafter shifted hori20ntally toward a second anchor A' through utiliæation of the other end portion of the link chain section 34.
Still further, Figure 9 illustrates the manner in which a cable C
may have one end thereof transferred from a first upright post P to a second upright post P' in somewhat the same manner in which the hoist 10 was used in Figure 8 to initially raise the load L toward the anchor A and to there-after more the load L toward the anchor ~'.
Also, as stated previously, when the control arm 94 is shifted toward the right end of slot 96, the brake mechanism is released, but the resistance to flexure of the arm 96 i9 controlled such that the arm 96 will flex when under the increased force required to release the brake mechanism when either end of the chain section 34 is supporting more than a minimum load. Accordingly, the brake release control arm can only be actuated to release the brake mechanism when there is substantially no load being sup~
ported by either chain section end.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A chain hoist including a support frame, rotatable input and output shafts journalled from said frame, stationary drum means mounted from said frame, first and second self-energizing wedge-type brake shoe means shiftably mounted from said output shaft for movement between applied and release positions and including first and second spring means, respectively, yieldingly biasing said first and second brake shoe means to the applied positions thereof for friction braking of said output shaft relative to said drum to prevent rotation of said output shaft relative to said drum in first and second opposite directions, respectively, a torque input member mounted on said input shaft for rotation therewith, connecting means drivingly coupling said input and output shafts for rotation of each by the other in opposite directions of rotation thereof, said connecting means including means establishing a limited loss motion connection between said shafts and control means operative to release said first and second brake shoe means responsive to torque input from said input shaft through said connecting means and to said output shaft above a predetermined minimum in said second and first directions of rotation, respectively, said control means also including abutment means engageable with said second and first brake shoe means for shifting said second and first brake shoe means to the release positions thereof against the biasing action of said second and first spring means responsive to said torque input to said connecting means from said input shaft in said second and first directions, respectively, during the take up of the lost motion in said connection as a result of rotation of said input shaft in said second and first directions, respectively, relative to said output shaft.

2. The hoist of claim 1 wherein said first and second brake shoe means each comprise a pair of brake shoe structures disposed on generally diametrically opposite sides of the axis of rotation of said output shaft.

3. The hoist of claim 1 wherein said frame included anchor means for anchoring said frame relative to a stationary structure.

4. The hoist of claim 1 wherein said frame defines a substantially closed housing in which said shafts are journalled.

5. The hoist of claim 4 wherein said shafts are coaxial.

6. A chain hoist including a support frame, rotatable input and output shafts journalled from said frame, stationary drum means mounted from said frame, first and second self-energizing wedge-type brake shoe means shiftably mounted from said output shaft for movement between applied and release positions and including first and second spring means, respectively, yieldingly biasing said first and second brake shoe means to the applied positions thereof for friction braking of said output shaft relative to said drum to prevent rotation of said output relative to said drum in said input shaft in either direction is below a predetermined low value.

7. A chain hoist including a support frame, rotatable input and output shafts journalled from said frame, stationary drum means mounted from said frame, first and second self-energizing wedge-type brake shoe means shiftably mounted from said output shaft for movement between applied and release positions and including first and second spring means, respectively, yieldingly biasing said first and second brake shoe means to the applied positions thereof for friction braking of said output shaft relative to said drum to prevent rotation of said output relative to said drum in first and second opposite directions, respectively, a torque input member mounted on said input shaft for rotation therewith, connecting means drivingly coupling said input and output shafts for rotation of each by the other in opposite directions of rotation thereof, said connecting means including means establishing a limited loss motion connection between said shafts and control means operative to release said first and second brake shoe means responsive to torque input from said input shaft through said connecting means and to said output shaft above a predetermined minimum in said second and first directions of rotation, respectively, said control means also including abutment means engageable with said second and first brake shoe means for shifting said second and first brake shoe means to the release positions thereof against the biasing action of said second and first spring means responsive to said torque input to said connecting means from said input shaft in said second and first directions, respectively, during the take up of the lost motion in said connection as a result of rotation of said input shaft in said second and first directions, respectively, relative to said output shaft, brake release means shiftably mounted from said frame for movement between active and inactive positions and operatively associated with said brake shoe means for shifting all of the brake shoe means toward their release positions only when torque loading on said input shaft in either direction is below a predetermined low value.

8. The hoist of claim 7 wherein said frame includes anchor means for anchoring said frame relative to a stationary structure.